Finite-element modeling on noise impacts and hearing in marine fauna

Abstract

Despite increasing interest in the effects of anthropogenic noise on marine fauna, relevant research is limited, particularly in those inaccessible species. Unfortunately, some of these inaccessible species are endangered, such as the little penguins (Eudyptula minor) and Australian sealions (Neophoca cinerea). In this study, we collected freshly deceased bight redfish (Centroberyx gerrardi), little penguins, and Australian sealion for medical computed tomography (CT)/microCT scans. Ear structures were reconstructed based on high-resolution imaging data for the three species. Moreover, 3D finite-element models were built to simulate the sound reception processes and ear responses to the incident planar waves from various directions toward the heads. The received sound pressure levels and motion (e.g., displacement and acceleration) of the internal ear related structures were computed. The data was used to predict the absolute hearing curves of the little penguins and Australian sealions. Our results also indicate that the motion difference plus the geometry of the otoliths plays an important role in the fish otoliths' response to incident sounds from different directions, resulting in different levels of damage to the hair cells. This study may potentially aid researchers in investigating the hearing of some other marine animals.